The invention relates to a wristwatch including a generator capable of converting mechanical energy to electrical energy, and more particularly, to a wristwatch having an oscillating weight and a permanent magnet rotor which is rotated by the oscillation of the oscillating weight so that induced voltage is generated in a coil and stored in an accumulator which provides an output to a watch circuit.
Electronic wristwatches are well known in the art and come in several different categories. A first such wristwatch utilizes batteries to power the time keeping structure. A great concern of watch manufacturers has been extending the lifetime of the batteries. One way to increase battery life is to use larger batteries. However, due to the inherent small size of the wristwatch, battery size is limited.
To overcome this problem solar batteries have been utilized in electronic wristwatches. A solar battery is provided on the display face of the watch. A secondary battery or a charging capacitor is charged by the solar battery to drive a clock circuit as shown in U.S. Pat. No. 4,653,931. These watches have been satisfactory, however, they suffer from the limitation that a black or blue solar battery is positioned on the face or dial severely limiting the watch design. This is not pleasing to purchasers who buy watches for aesthetic value.
Another type of watch includes a mechanical actuating member such as an oscillating weight housed within the watch. A permanent magnet rotor contained within the watch is rotated by movement of the mechanical actuating member to generate electrical power. This watch has also been satisfactory, however, because of the size of the generator itself increases with the need for more power obtaining additional power for the wristwatch has not yet been perfected.
Accordingly, it is desirable to provide an electronic wristwatch with an electric generator which overcomes the shortcomings of the prior art devices described above.